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Ken Martwick wrote:
>
> When a PC first boots, the BIOS provides (real-mode) 
> interrupt service via an array of 256 "interrupt vectors" 
> These do not normally concern Linux, but they do affect 
> the booting process if loadlin is used and have a major 
> impact on the compact Xvesa server.  

Congratulations Ken, you have found the source of the
Xvesa problem.

> Assuming the BIOS interrupt vectors are good
> the problems begin when DOS boots and adds its
> changes to the vectors; 

These "changes" don't appear to be necessary.  After
running your fix program, my DOS TSRs still work fine.  
DOS doesn't appear to need those vectors after the 
TSR has been installed.  What's happening (I suspect)
is DOS is leaving junk in the vectors (instead of
restoring them to their defaults).

> My first idea to correct the Xvesa problems was 
> to write a "clean" set of BIOS interrupt vectors 
> into memory after BL3 boots.  

You don't have to wait that long.  I'm currently
running your fix in my autoexec.bat (immediately
after smartdrv is installed).  Smartdrv works 
perfectly.  Xvesa works perfectly.

> my idea was to only "correct" some of the altered 
> vectors.  In fact, I wrote a quick program to change 
>  the first 32.

You obviously caught the problem vector(s) in that 32.
It would be useful to figure out exactly which vector(s)
is the problem.  Perhaps that vector has a common default
in all BIOSes?  Or perhaps there is a common way to reset
that vector to its default setting?  Then we could produce 
a simple fix program that would work on all systems.

> seems to work flawlessly and to allow booting from a
> "normal" DOS environment with XMS ("himem.sys" or equal).  
> I do not use emm386, so I cannot say if it would work.  

It works for smartdrv too.  

> Tests were conducted using PTS-DOS and FreeDOS.

I did my testing on MSDOS 6.0.

> In practice, the messiest part of this procedure is 
> getting a clean set of interrupt vectors.  

How different are the default vectors in different BIOSes?
Are the default values not (permanently) stored somewhere?  

> I have found a "multiboot"program which comes with 
> utilities to do this with the useof a temporary boot 
> floppy.  

That's the really complicated part.  We can't expect a
new user to go through all that.  It's a long way from
unzip-and-go.  And it's not a good "look" for BasicLinux.

Cheers,
Steven

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